Variable load brake



Jan. '11, 1949.

H. N. SUDDUTH VARIABLE LOAD BRAKE Filed Nov. 25, 1944 m mm mm ZSnventorfile/21pm swam (Ittorneg;

' the brake pipe on the car.

Patented Jan. 11, 1949 UNITED {STATES PATENT OFFICE VARIABLE LOAD BRAKEHenry Norton Sudduth, WatertownnN. Y., as-

signor to The New York-Air Brake Cmpany, a corporation of New JerseyApplication November 2 3 Claims. (01. 303-22) This invention relates toair-brakes'and particularly to freight brakes of the variable load t p-Present trends indicate that, 'in the not distant future, freight carswill be of materially lighter construction without reduction in theloads to be carried by the cars. In'consequence the ratio of loadedweight to light weight will be increased beyond thelimit permissiblewith the present AB brake equipment. I

The type of car and type of load to be carried is such that partialloading must be compensated for, so that some form of variable loadbrake must .be adopted. Sincethe 'AB brake valve will remain standardfor all freight cars used in interchange service, any variable'load'brake to be acceptable for general adoption must use the AB valve.Moreover'it must preserve the basic operating characteristics of thatvalve, since cars equipped with the proposed variable load brake mustoperate in trains which will include old cars having standard AB brakeequipment; These facts impose severe limitations, and create a dif-"ficult problem.

It has heretofore been proposed to construct a variable load brake inwhich use is made of a brake cylinder (hereinaftercalled the lightcylinder) which is adequate to'perform braking functions on an unloadedcar, and with which is used a second brake cylinderlhereinafter calledthe load cylinder), which isbrought into action on loaded cars onlyafter the li'ght'cylinder has brought the brake shoes intofrictionalcontact with the wheels. The load cylinder is then latched tothe brake rigging, "and'being designed with a minimum piston clearanceis put under pressure with the minimum practicable expenditureofair.

The admission of air to the load brake'cylinder is controlled by avariable ratio relay which is piloted by the braking pressure'in thelighticylin- 'der and develops a proportional pressure in" the loadcylinder.

The ratio of.v such "proportional pressure to the pressure in the lightcylinder is determined by a lever mechanism forming'part" of the relayand having a shiftable fulcrum. This fulcrum is positioned accordingto'the load on the car. I I I Some features of the present inventioncould be .used with any of various known mechanisms suitable to positionthe fulcrum in relation to' the load on the car. It is desirable touse'a mechanism which performs this fulcrum adjusting function duringthe'initial phase-of charging of trated at I 'and'the truck bolster at2.

s, 1944, Serial No. 565,130

.it by. a very simple mechanism, and tends to assume no-load settingunless it functions as.

intended.

Another objection to prior art devices was that during cyclingin gradework with retainers set, the'load brake cylinder was exhausted duringrelease operations. In consequence muchair was wasted. l

Accordin to the present invention the load cylinder and thelightcylinder are both subjected to control'by the retaineriand controlled insuch a waythat they'funetion harmoniously during cycling with'retainersset. V

Thus the invention offers a number of very .important refinements buttakes advantage of certain known principles to carry out some of its'functions. a: i

The invention'willnow be described with reference to the accompanyingdrawing in which:

- Figure 1 is. a diagrammatic section of the load controllingmechanism'drawn on as large a scale as conditions permit and shownconnected to the brake cylinders, reservoirs, AB valve and. retainer,all drawn in miniature.

Figure 2 is an enlarged view of the pilot valve. Figure 3: is anenlarged view-ofthe valve portion' of'the relay.

The drawing shows aworkable embodiment, but is diagrammatic to theextent thatall ports are shown" in a single plane. More compactcommercial arrangements can readily be designed 5- according to wellknown principles. 4

The drawing shows the system uncharged and under no load conditions. r

. Since the car truck and the AB brake valve are basic elements'to whichthe invention is applied, these will be described first to develop theenvironment in which the invention will be used. Pedestals of aconventional car truck are illus- Springs 3 supportth'ebolster-on thetruck.- The bolster is shown at its uppermost (unloaded) position fromwhich load on thecar will depress it relativelyto ment 4 of the brakepipe is illustrated, since its connections and control followstandardpractica The brake pipe 4 is connected to the pipe bracket 5 onwhich aremounted the emergency portion 6 and service portion l of the ABbrake valve. Piped individually to bracket 5 are the" emergencyreservoir 8 and .thezauxiliaryyreservoin 9. From bracket 5 a branchedpipe H leads to a supplemental reservoir l2 and to thevariable loadmechanism. A supplemental reservoir 12 is not: usediwritlz:ttli'eregular: brake: valveg. but is'l'xereprovidemtmfumish airsto the loadcylinder. Itsis. chargedtdirectly frombrake? pipe? 4 through atclreckvalveiancilaiilow restrictingichoke: which arerrrotshown: but woulddesirabhwbemountedun t bracket: 5. It: is: known: practice: so;torcharge I a supplemental: reservoirrwhere. one: is needed: to actuatea: loadi cylinder: Consequently illustration of the: path. for chargngtthe: supplemental! reservoi-n- IQ: is deemed? unnecessary:

The; usual: brakes cylinder pipe"; (312 leads :to 1 the lightbrakescylinder: 4 hand: hasaa' branch leading to. they variable: loadimechanism. to: be: described.

Thezretainer pipe-.2 l5:leadsttoethetusualiretainer l6 and has a branchleading to the varia'hle load {mechanisms The-above namedzcomponentsiexcept" thezparts H and; i2 and: the connections: toz-the variable load.mechanism: are: standardz valve:- and freight car equipment. To theseare acidedia I load 1sensingmechanismzandzazyariable loadzrelay valve:which-:controlsttlierloadrcylinden, The variabledoadl mechanism:controls; admissionand= exhausts-of motive airrtoi andlfrumi the loadbrake cylinder l1. by wayrof load cylinder pipe and passage! 8:-Therpiston'in light cylinder l4 operatesilever 1-9 tlnoughlthe: usual:pushf-rod -23; Gylinden M" always; operates; advance of load cylinderl1 and so causes lever la to -draw push-rod. 22; outwards! relativelyttr the: stilIEJretraeted-tubularJpiston'rodl23zoficylinder 1:1. The fdistance: moved: depends; om the;- running: slack. When load. cylinders:If]! is:-= operated; latchi 24 clutchess piston irodi2l3rto. pusherodzfls. Theraclutch iS -Of: 8% type-which; disengagesiaon'ly; when pistonrod 23 retreats to itssfulhrelease: (innermost) positioniTheicylind'ertandElatch; arrangement iaimdaily use in light and loadbrakes, andasincefitsrfunctions: arefamiliar; requires: no: detailedde-- .scription;

The. variable loadmechanis-m. is enclosed in:a housing generallyindicated:- at- 25: and madeup of castings havingrthe necessaryiports;and-.p as- I sagesshereinaftert describedz. Pipes:andipassageswhich are in free communicatiomwithronmanotherarerdesignateda by the'same references numeralin: order to minim-izeetheuse-of: reference numerals; on. tlrez drawing I and; simplify. thedescription.

The: relay proper-comprises: twozmovable :abutmeats; shown as.flexiblediaphragms 2.6 and 21 ofrequal areas. Thesearerclampedatitheirrmargins between: separable portions of 1 the; housing as shown;'Eachdstsubjeet; onxitsrlower face: to'

4 atmospheric pressure, the spaces below the diaphragms being open tothe chamber 28 which is vented to atmosphere at 29. The chamber 43 abovediaphragm 26 is subject at certain times to pressure developed in thelight brake cylinder M. It reacts downward on the enlarged head of thevertically guided thrust member 3|. The diaphragm'ZT-lcarries, atitsacenter'azported hub 32. The lower end of the hub 32' ispinned to therighthand end of a lever 33, the other end of which is in thrustengagement with a thrust roller on-the lower end of the thrust member3|. The lever 33 has a shiftable fulcrum which takes the-:formzofzalroller 34 whose journal is guided horizontally bw a fixed guide slot 35.The port through" hub 32* is controlled by a poppet type exhaust-valve35s which is biased in an opening direction (upward) by a coilcompression spring 3T mounted in the hub beneath it.

The pipe ll already described as connected to thatsupplementalreservoinit leads: through a strainer: 3ih'to: a; chamber" 39.-'in..the body!'25: A poppet inlet valve which opens toward; the chamber: 39 1 5;biasediin: azclosingidirection by; an overlying. coil; compressionspring; M; as shown and. has as. downwardl extending: pilot. which: isaligned with and: arranged tmentenintortlnrust engagement with; the:exhaust. valve; 36: Ilhe partssa-rer'solarrangedfthat:iii the.diaphragm; it! is forced upward, the effect is first to:seat:theexhaustzva-lve-3E andzthenFunseatzthe'inletior supply valve": 40:admitting: airr from: the: supplemental reservoir: l 2-.to wtlriespacedzabovecthe :diaphragm. The: space: 4% is: connected: by; thepassage: and communicatingrpipe t8 withithe1oadrcvlinder I l During;brake: applications: and I after: a definite messureshaswbeenwdeveloped.in $118; light: cylinder 14; .thea pressure: acting inrthalightx-cylinder- 1411s permitted to act .in:- the space-.- 43' above:the: diaphragmlzfii. This aetion; isitimed :and controlled by aapilotvalve: mechanismibest shown in .Eigure 2; This. comprises: a.differential pair of. diaphragms; namely; at large. diaphragmx 441 and;a

smaller diaphragm 45 reacting upononeanother atthei-r-rcentersnimonewvam thrustthrougha stem in-freecommunicationwithithe =pipe l3r andzconsequentlm:withithetlightzcylinder-r I4. Thezspace 348: between the: twwdiaphragms ll S- connectedby abranchedlpassagew-with the. chamber lliabove diaphragmi 2'6:andwith; as valve chamber; 50. A lav-pass; cheolezvalve-S I:permitsxflow: f rom: chamberswftopassage I31.

Al spider: 52 is; biased: to: the: right as viewed in thezdrawings by;coilcompressiomspring; 53

andiis inrthrustl engagements with .di'aphragmi 4-5 and stem 46. Itcarries on its end a release valve 60; seatz formed: inlthe end: oii atubular stem 55 of a: p pet; valve: 56wwhichiopens::when1 moved. in alefth'and :dilYBCtliOIliflHfiLVl/hifil'l'; is: biased closedtbya-coihcompressionaspringfi'h The: pilot' of valve 54tisguidedf in thebore-f: the stem. There K islaniannularl-groove r58=which7 encircles;the tubuwhich tlrwspring 53: and; SDidIT5Z-L are; mounted,

is'lin: free *eommunicationawith the retainer: pipe Withrthe theareleasepositiomshownnin the drawing the spring-imholdsstheediaphragms 44. andto the right so that the exhaust valve 54:;is open and so that the valve56 is closed byia spring 51. Consequently chamber 43 ,above diaphragm 26is disconnected from the ,light brake cylinder l4 and is connected tothe retainer pipe. Hence it is connected freelyto at.- mosphere if theretainer ,l'6 is not set; and is controlled by the retainer when thelatter is set.

The diaphragms 44 and 45 are of such areas and the springs 53 and 51 areof such strengths that if a pressure is developed in the light brakecylinder l4 sufficient to bring the brakeshoes against the wheels, thespring 53 will be overpowered and the valve 54 will be closed. For thisa brake cylinder pressure of approximately 8 lbs. will be assumed. Anincrease in pressure in the cylinder M to say 13 lbs. will overpoweralso the spring 5! and open the valve 56 connecting the light brakecylinder l4 with the space 43, above the diaphragm 26. i

It will be observed that any pressure which is developed in the passage49 will be admittedto the space 48 between the two diaphragms 44, and

4,5. The areas of the diaphragms are so chosen that as a brakeapplication is increased in intensity the pressures in the two brakecylinders I 4 and I! tend to become equal at full service (i. e. at fullequalization). In other words when light brake cylinder pressurecorresponds 1 to full equalization, that is approximately lbs., thepressures in spaces 41 and 48 become approximately equal. In consequencethe diaphragm 4d becomes ineffective. The area of the diaphragm 45 issuch that it can just hold the o valve 54 closed against the reaction ofspring 59 when 50 lbs. pressure exists in the space 48. An increase ofpressure above 50 lbs. in the space between the two diaphragms such as.would occur during emergency applications, will cause the l diaphragm 45to move to the left and hold the valve open.

upperendaof lever 66 and forces it out as far as lug 65, permits. Thisaction occurs when port 75 isput under pressure bymeans to be described.

Axially aligned with cylinder 12 is a somewhat smaller cylinder 16 inwhich a piston Il may be forced out against a return spring 18 until theend of its rod-19 engages the end of lever 66. Air'to actuate piston 11is delivered through a side'port 8| in cylinder 12 to a passage 92 whichleads to the headend of cylinder it. This assures that-piston. 69 mustmove at least a short distancebefore piston ll can be energized. Thisisidle motion of piston 69 necessary to reach full-load'position. Ittimes the pistons so that piston69:moves before piston 11 moves, andserves as a safeguard in the'event that piston 69,

or the cable 62, or related parts should fair to Since American railwaycars are mounted/onv bogie trucks and since the spring suspensionis inthe trucks, a flexible connection is needed be- J tween a load sensingcomponent on the truck and the fulcrum adjusting mechanism on the body.According to the invention this connection takes the form of a Bowdenwire, and is so contrived that the wire acts in tension. This last isdesirable, but not strictly necessary, slncea Bowden wire can be made tooperate in compression. An important feature (here illustrated but notthe invention of this applicant) is an, arrangement such that the Bowdenwire isinert, except during the load sensing operation; This greatlyreduces wear.

A flexible tubular casing BI is attached at one end to housing 25 and atthe other end to a pedestal I. 452. The lower end of wire 62is pinned toa feeler It houses a flexible push-pull wire lever 93 pivoted at 64 inthe pedestal, and capable 0f being drawn up until it engages alug 65 onbolster 2. The distance it can be sodrawn up diminishes as the load onthe car is. increased. The upper end of wire 62 is pinned to a lever-65- which is fulcrumed near its middleon a jo rnal 91 carried byhousing 25. The wire is biased .to the position shown by atension spring68, .which is located in housing 25 rather than on pedestal Isimply toprotect it against damage.

'A single acting piston 69 with return spring II in cylinder 12 operatesa push-rod 13. This carries an adjustable head 14 which engages the.

function. In such case piston I! will retreat to no-load position whenunlatched by the latch described below.

:Rod19 is toothed and may be locked by a latch 83=held normally engagedby spring 84"and releasable 'bypiston 85 which is subject to pressure inpassage 15.

1 A'collar86 on rod 19 engages one forkedend of bell""crank 81 which ismounted on journal pin' 'fiii carried by housing 25. leverBTisbiased toturn counterclockwise (as viewed in Fig. l)' by a tension spring 99. Theother forked end of bell crank 81 engages a pin 89 on the lower end oflink 9| connected to the journaliof roller 34. The pin 89 .works in aguide slot 92 in housing 25.

The use of a link 9| with its'ends guided by slots =92ancl 35 arrangedas shown has the effect of making the force ratio of the relay varynearly in strict proportion to the displacement of piston ll-which is inturn substantially proportional to the load on the car. This linkage isthe invention of another and hence is not claimed in the presentapplication. Where less precise proportioning is sufficient, otherconnections between piston-Hand roller 34 may be used.

' It should be observed that the ratio controlling means (roll'er34),has a positive connection with bell crank 91, and is biased toward lowratio position by spring 90. This spring holds bell crank 81' in thrustengagement with collar 86 on rod 7950f piston 11, so that the bell crankand piston move together. The spring 18 prevents the piston fromundulyloading spring 99, but is not ordinarily effective to move thepiston independently of thebell crank.

To-develop pressure in port 15 andthen vent thatjport during initialcharging of brake pipe 4, use isymade of a cutoff valve which is, the

.mechanismenclosed in housing 93.

A pipe 94 which, is simply a branch of brake pipe 4, leadsfrom bracket 5to valve chamber 95 in housing 93. In chamber 95 is a seat for slidevalve 96. 'Thegendof passage 15 isexposed in this seatv as fis;:the,endof an exhaust passage 91. The slidefvalve has a cavity as shown and isso dimensioned that in its lower position it exposes :passage 15 andblanks exhaust passage 91, while in its upper position it connectspassages 15 and'91. f r

Valve 96 is shifted by stem 98 attached to the The bell crank cylinderto start to apply after and to fully release before the light cylinderstarts to apply and fully release, respectively; and means associatedwith the pilot valve for subjecting the final releasing action of therelay to control by the retainer.

3. A variable load brake mechanism comprising a light brake cylinder; aload brake cylinder; a retainer for limiting the release flow from thelight brake cylinder; a pressure controlled relay adapted to operate inresponse to braking pressure in the light brake cylinder and serving toadmit air to and exhaust it from the load brake cylinder; a pilot valveadapted to delay the initial development of controlling pressure on therelay at the start of application and to vent said pressure and sorelease the load cylinder when the light cylinder braking pressurereaches a low value but prior to full release thereof; and connectionswhereby said venting action is subjected to control by the retainer.

4. A variable load brake mechanism comprising a light brake cylinder; aload brake cylinder; a pressure controlled relay adapted to operate inresponse to braking pressure in the light brake cylinder and serving toadmit air to and exhaust it from the load brake cylinder; a pilot valveadapted to delay the initial development of controlling pressure on therelay at the start of application and to vent said pressure and sorelease the load cylinder when the light cylinder pressure reaches a lowvalue but prior to full release thereof; and a retainer serving tocontrol releasing fiow from the light brake cylinder, and to inhibitrelease of said load cylinder which would otherwise occur when pressurein the light cylinder reaches said low value.

5. A variable load brake mechanism comprising a light brake cylinder; aload brake cylinder; a retainer for limiting the release flow from thelight brake cylinder; a, pressure controlled relay adapted to operate inresponse to braking pressure in the light brake cylinder and serving toadmit air to and exhaust it from the load brake cylinder; a pilot valvecontrollable by a pressure differential between the two brake cylinders,and serving to connect the light cylinder in controlling relation withthe relay when pressure in the former reaches a chosen value, anddisconnect the same and vent the relay when light cylinder pressurefalls to a chosen value; and connections whereby the retainer whenactive limits the venting action of the pilot valve.

6. In a variable-load brake, the combination of a relay for modifyingthe intensity of brake applications; ratio controlling means adjustableto vary the setting of said relay progressively between no-load andfull-load settings; normally retracted load-sensing means; a movablestop positioned by motion of the load-sensing means; a first motorserving when energized to move said load-sensing means to itsload-sensing position and thus position said stop according to thesensed load; means biasing said ratio-controlling means toward itsno-load setting; a. second motor serving when energized to move saidratio adjustmg means in opposition to said bias to settings determinedby said stop; and controlling means for energizing said motorssequentially in such order that the first motor is energized and movesthe load-sensing means to sense the load and set the stop while thebiasing means moves the ratioadjusting means and the second motor towardno-load setting, and then both motors are energized whereby the secondmotor moves the ratio adjusting means to a setting determined by theposition of said stop.

7. In a variable load brake, the combination of a relay Ior modifyingthe intensity of brake applications; ratio-controlling means adjustableto vary the setting of said relay between a no-load setting and a seriesof load settings; normally retracted load sensing means; relay-adjustingmotor means adapted to be controlled according to the load-sensingpositions assumed by said load-sensing means when projected; normallyrestrained yielding means serving to bias said adgusting means towardsaid no-load setting; and control means serving periodically to projectthe load-sensing means and free the biasing means, and while theload-sensing means is so projected and after a time interval in whichsaid biasing means is free to act, serving to energize therelay-adjusting motor means and cause it to effect an adjustment inopposition to said biasing means.

8. In a variable-load air brake, the combination of a brake-controllingvalve device; ratiocontrolling means associated therewith, and having aseries of settings in which it serves to establish a series of brakingratios appropriate for loads from no-load to full-load; means biasingthe ratio-controlling means toward its no load setting; a latch normallyeffective to hold said ratio-controlling means in its adjustedpositions; a. first pneumatic motor for disengaging said latch; anormally retracted load-sensing means including a, stop for arrestingthe ratio controlling means, and positioned according to the sensed loadwhen the sensing means is projected; a second pneumatic motor forprojecting said load sensing means to its load-sensing positions; athird pneumatic motor for shifting said ratio-controlling means againstthe urge of said biasing means until arrested by said stop; and a'controller operable periodically to supply motive air to the first,second and third motors in the order stated, then vent the first motorand thereafter the other two. i

HENRY NORTON SUDDUTH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,650,309 Whitaker Nov. 22, 19272,418,013 Cook Mar. 25, 1947

